Circuit controller



July 28, 1942.

E. H. AYERS ET AL CIRCUIT CQNTROLLER Filed Sent. 17, 1940 Fig.3.

Fig. Fig. 2.

' In 5 41/07! on In a u/af/cn m y r m ow r O fi i QVVwaW A P F m En h ofits drop out impulse. reclose, it will immediately drop out because ofPatented July 28, 1942 CIRCUIT CONTROLLER Edgar H. Ayers, Schenectady,N. Y., and Wilbur W. Warner, Fort Wayne, Ind., assignor to GeneralElectric Company, a corporation of New York Application September 17,1940, Serial No. 357,126

13 Claims.

torque motors, especially where the supply frequency is relatively low,difiiculty is often en'- countered because of repeated reclosures of'the relay as the starting period draws to a close. As the motor picks upspeed and the starting current decreases, the drop out point of therelay is approached. When the relay drops out and excludes the startingwindings from the circuit,

the overall impedance of the circuit is reduced due to mutual inductionof the motor windings and the phase relationships of th currents. .Undersuch conditions there is danger that the relay .will again pick up dueto the increased motor current passing through its operating coil.Danger of such reclosure is enhanced if the relay armature is stilloscillating under the influence If the armature does the decrease ofmotor current caused by the insertion of the starting windings in thecircuit.

Accordingly, it is an object of our invention to provide means forrestraining oscillation of a relay-armature after a single. operatingimpulse has been applied or removed.

It is a further object of our invention to provide, in a relay subjectto increased operating force upon drop out, means for dampingoscillations of the armature in order to prevent reclosure while theoperating force again decreases.

Further objects and advantages of our invention will be apparent and theinvention itself will be better understood from the followingdescription taken in conjunction with the accompanyin drawing, and thefeatures which we believe to be novel and patentable will be pointed outwith particularity in the appended claims. In the drawing, Fig. 1represents a front elevation of a controller embodying our invention;Fig. 2 is a left side elevational view of Fig. 1, partly in section;Fig. 3 is a right side elevational view of Fig. 1; Figs. 4 and 5 arefront and side views respectively of a relay core adapted for use inconnection with our invention; and Fig. 6 is a circuit diagramofconnections for a controller embodying our invention to a typicalrefrigeration motor circuit.

Referring now to the drawing, we have shown our invention in one form asapplied to a starting and overload controller fora split-phase motorused in connection with a refrigeration system. However, it will beobvious that our invention has broad application to motors requiringspecial starting means. The controller is mounted on a base H! ofsuitable insulating material having a vertically projecting dividingwall ll running longitudinally of the base Ill. The wall ll serves tosegregate a thermally actuable overload responsive device 1l2 from themajor portion of an alternating current starting relay l3 secured to thebase I0- Thestarting relay l3 comprises a magnetizable substantiallyU-shaped frame l4 curved edgewise and having a core portion l5 providedwith a pole face l6. Encircling the core portion l5 and insulatedtherefrom by a cylindrical insulating jacket I1 is an energizingwindingv l8, the ends of which are covered by insulating shields IS. Thewinding I8 is connected between a point 20 on the frame l4 and aterminal 2| secured to the base 10. l The frame It rests upon and issecured to the upper face of the wall II by fastening means such asrivets 22 and 23 and has an intermediate portion 24 overhanging theoverload contactor I2.

Former at the other end of the frame 14 is a supporting member 25 towhich is secured one spring 26 normally supports the armature 21 inspaced relation to the pole face It of the magnetizable frame M so as toform an air gap between the armature and the frame. Secured to thearmature 21 adjacent to the end nearest the air gap, we have provided ashort circuited winding 28 comprising a double turn coil of highlyconductive material, such as copper, the purpose of which will be morefully described hereinafter. The winding 28 may be conveniently securedto the armature by means of a finger 29 which we have shown pressed fromthe main body portion of the armature 21.

Extending from the armature 2'! is a spring finger 30 which supports atits free'end a movable contact 3! in cooperating relation with arelatively fixed contact 32 carried on a supporting arm 33 of a terminal34 fixed to the base l0. A projection 35 on the backside of the movablecontact ii is arranged to limit movement of the armature 21 toward thepole face It by engaging the adjacent side of the short circuitedwinding 28.

In order to damp vibrations of the armature 21 under the influence ofincreased energizing current after dropout or under the influence of thespring 26, we provide a friction damping mechanism comprising a yoke 40carrying a spring finger 4| and pivotally supported upon a bracket 42mounted upon the supporting member 25 of the frame i4. The spring finger4| may be fastened to the yoke 40 as by riveting at the point 43. Theassembly comprising the yoke 40 and the spring finger 4| is pivotallymounted upon the bracket 42 for rotation about a point spaced from thepoint of attachment of the spring 26 to the supporting member 25. By

- way of example, we have shown the bracket 42 provided with three ears44 cooperating with slots formed in the yoke 40. Th oke 40 fits looselyover the ears 44, and may be held in place by a pin 45. As is shown inFig. 2, the armature 21 is embraced between the free end of the springfinger 4| and the upper horizontal arm of the yoke 40. The bias of thespring 4i i such that it engages one side of the armature 21 at a point4ia intermediate its ends and holds the upper horizontal arm of the yoke40 in engagement with the other side of the armature at a point 4ib. Itwill now be apparent that any rotational movement of the armature 21will result in relative longitudinal movement between the armature 21and the spring 4i due to the spaced mounting of the armature and thspring. Such relative longitudinal movement produces friction whichtends to restrain vibration of the armature.

It will be noted that the point 4la is spaced a short distance along thearmature 21 from the point Mb. The spacing of the points of contactresults in a rotational force upon the yoke 40 such that the lowerhorizontal arm of the yoke 40 is biased toward the base Iii. This biasof the yoke 40 against the bracket 42 tends to me vent chattering of thyoke upon the bracket, and provides a minimum spring force for a givenpressure at the point lla.

In order to prevent undesirable oscillation of the armature 21 upon pickup of the relay, we have provided the frame l4 with a twisted coreportion i and a sloped pole face it, Normally the movement of thearmature 21 toward its attracted position stores suflgcient momentum inthe armature to throw thespring finger 20 and the contact 3i forciblyagainst the fixed contact 32. Deflection of the spring finger 20 againstthe fixed contact 32 produces a force tending to move the armature backfrom its attracted position to its deenergized position. The bias of thecantilever spring 28 also tends to produce such movement in thearmature. To prevent such undesirable oscillationwe provide acontinuously decreasing air gap as the armature approaches its attractedposition under the pole face l8. As best shown in Figs. 4 and 5, theplane of the upper part of the core portion II is parallel to the baseplate i ii, while the plane of the lower part of the core portion l5forms an angle with the base plate Iii, preferably an angle ofapproximately 45 degrees. While the twisted core portion describedbrings the armature 21 directly under the pole face It for a' greaterportion of its movement than if the plane of the pole face were parallelto the base plate It, we also provide means for varying the length ofthe air gap between the p le face II and the armature 21 while thearmature 21 is directly under the pole face. To this end the pole faceIt is cut to form a small angle with the plane of the insulating washerIt. This is best shown in Figs. 1, 2, and 3. The core portion ii of theframe l4 may also be provided with means for holding the coil I. inplace. As shown in Figs. 4 and 5. we have provided for this purpose anear 46 pressed from the core portion II and bent to form an angletherewith. With the above construction a continuously increasingmagnetic force is applied to the armature 21 as it approaches its pickedup position under the pole face IS. The increasing force resulting fromthe continuously decreasing air gap holds the armature 21 positively ina closed position against the force of the springs 24 and 20, and thetendency of the armature 21 to oscillate is minimized.

In order to dampen oscillations of the armature 21 which might beproduced by the alternating character of the electromotive forcesupplied to the coil I2, we hav provided the short circuited windings 28attached to the upper end of the armature 21. As is well understood inthe art, the damping effect of the short circuited winding 28 is duemainly to the out-of-phase fiux produced by the circulatingcurrentinduced in the winding by the changing main fiux from the core memberII.

Referring now to the overload responsive device i2. we have provided aU-shaped adjustable supporting member iii fixed to the base ill by arivet or other suitable fastening means Ii and provided with a threadedadjusting screw 52 exstrip 42 is arranged to deflect downwardly with arise in temperature, and carries on its upper face a movable overloadcontact 54 in normal engagement with a relatively fixed overload contact55 which is mounted on a resilient strip 5! of conducting material. Theresilient strip It is attached by brazing, riveting, welding or othersuitable means to the overhanging portion 24 of the frame l4 in goodelectrical connection therewith.

On the lower face of the bi-metallic strip I2 is secured a disk-shapedarmature 60 made of magnetic material such as soft iron, and positionedto be attached into engagement with a permanent magnet 6i fixed on thebase l4 below the armature Ill. The magnet 8i preferably is made of analloy having a high coercive force and consisting essentially ofaluminum, nickel, copper and iron such as is described and claimed inUnited States Letters Patent 1,947,274, issued February 13, 1934, toWilliam E. Ruder. We prefer to form this magnet material into a buttonor disk shape having a central groove running diametrically across theupper face thereof and suitably magnetized to have a north pole and asouth pole on the upper face and adjacent to the armature 40. We providemeans for heating the bi-metallic strip 52 by locating a resistanceheater l2 beneath the strip. The heater .2 is spaced from thebi-metallic strip 52 and from the base I. and has one of its ends inelectrical connection with the fixed end of the bi-metallic strip 82 andthe other of its ends in electrical of resilient material having anupwardly extend ing end arranged to press against the bi-metallic strip53 in its attracted position. The stop 65 is carried on a pair ofabutments 65 projecting from the base land is threaded at the middle toreceive a screw 61 which may be used to adjust the strip 65. to raise orlower the end which comes in contact with and limits the downwardmovement of the bi-metallic strip 53.

Referring now particularly to Figs. 1 and 6,

' the electrical circuits through our controlling relay, when connectedto a split-phase motor, may be traced. The supply wire 10 of Fig. 6 isconnected to a thermostat 1| which operates in accordance with thetemperature of the refrigerator cooling compartment in a manner wellknown in .the art. From the thermostat II the circuit continues throughthe line terminal 63 of the relay and then through the heater 62 and thebi-metallic strip 53 in series to the contacts 54, 55. From the contact55 the starting circuit of the motor M may be traced through theresilient strip 56, the frame M, the spring 26, the spring finger 30,the relay contacts 3|, 32, the terminal 34, the wire S and the startingwinding of the motor back to the supply line I2. A parallel, circuit forthe running winding of the motor M may be traced from the contact 55through the magnetic frame 14 to point 20, the coil l8,

the terminal 2|, the wire R and the running winding of the motor back tothe supply line 12.

In the operation of the circuit controller diagrammatically representedin Fig. 6, the thermostat II is first actuated to connect the winding l8to thesupply line 10 through the heater 52,

the bi-metallic strip 53 and the contacts 54 and 55, A circuit is thuscompleted through the winding l8 and the running winding of the motor inseries. standstill, the resistance of its running winding is very low.Therefore, a large surge in current will flow throughthe winding I8.Such energization of the winding l8 magnetizes the frame l4 sufficientlyto attract the armature 21 toward the pole face Hi to close the contacts3|, 32. Engagement of the contacts 3|, 32 completes a circuit for thestarting winding of the motor M in.

Since at this time the motor is at a results in an increase in currentthrough the winding l8 and the consequent danger of reclosure of thecontacts 3|, 32. According to our invention such reclosure is preventedby the friction damping mechanism 40, ll.

The thermally actuable overload device I2 is so adjusted that for normalrunning conditions the heat from the heater wire 62 is insufficient todeflect the bi-metallic strip 53 to an extent sufflcient for thearmature 60 of the strip 53 to be attracted' to the permanent magnet 5|.Neither does the initial high current which flows in the heater wire 52,when the motor is just starting, cause the strip 53 to be deflectedsufficiently to be snapped to the magnetically attracted position. Thishigh current flows for a relatively short time and quickly decreases toa low value as the motor M accelerates. However, should the motor Mrefuse to start, or be stalled for any reason, or should a condition ofoverload occur during operation, the resulting high current through theheater wire 62 will quickly cause the bi-metallic strip 53 to deflectand be magnetically attracted. The overload contacts 54, 55 willtherefore disengage and interrupt the fiow of current to the motor M.

While we have shown a particular embodiment of our invention, it will beunderstood, of course. that we do not wish to be limited thereto sincemany modifications may be made, and we therefore contemplate by theappended claims to cover any such modifications as fall within. the truespirit and scope of our invention.

What we claim as new and desire to secure'by Letters Patent of theUnited States, is:

1. In a circuit controller, a magnetizable frame, a magnetizablearmature having one end v movably mounted upon said frame and asubstantially rigid free end arranged in' attractive relation to saidframe, 'means for magnetizing said frame to attract said free endthereto, and means for restraining oscillations of said armafur ecomprising a resilient member pivoted to said frame at a point spacedfrom said one end slidably to engage said free end of said armature.

.2. In a circuit controller, a magnetizable frame, an armature mountedfor' movement about a fixed point at one end and having a substantiallyrigid free end adjacent said frame but biased to a normal positionspaced therefrom, means for magnetizing said frame to atparallel withthe coil l8 and the running winding of the motor M. As the motor Maccelerates, the current flowing through its running winding and therelay l8, as well as through the starting winding of the motor,decreases in a manner well understood in the art. When the currentflowing through the winding l8 has diminished to a predetermined point,the winding i8 is no longer able to hold the armature 2'5 in itsattracted position. The armature 21 thereupon drops out and opens thestarting circuit of the motor Matthe contacts 3|, 32. In a high startingtorque split-phase alternating current motor of the type with which ourinvention is particularly applicable the mutual induction of thestarting and running winding is such that when the starting winding isdeenergized the overall impedance of the circuit between the contact andthe wire I2 is decreased. As has been previouslyexplained, such adecrease in impedance tract said free end thereto, and means forrestraining oscillations of said armature comprise ing a resilientmember pivotally mounted at a point spaced from said fixedpoint slidablyto engage said free end of said armature.

3. In a circuit controller, a magnetizable frame, an armature having asubstantially rigid movable end biasedt a normal position spaced fromsaid frame, means for magnetizing said frame to attract said armature,thereto, and means for restraining oscillation of said armaturecomprising a resilient member pivotally mounted independently of saidarmature to frictionally engage said movable end of said armature.

4. In a circuit controller, a member mounted for oscillatory movementabout a first fixed point, and a resilient member mounted foroscillatory movement about a second fixed point spaced from said firstfixed point and frictionally engaging a substantially rigid portion ofsaid first member at a point spaced from said first fixed point.- e

5. In a circuit controller, a magnetizable frame, a magnetizablearmature having one end resiliently mounted upon said frame and asubstantially rigid free end biased to a normal position spaced fromsaid frame, means for magnetizing said frame to attract said free endthereto, and oscillation restraining means comprising a yoke and springassembly pivotally mounted "upon said frame at a point spaced from saidone end of said armature and engaging said armature at a pointintermediate its ends.

6. In a circuit controller, a magnetizable frame, a magnetizablearmature movably mounted to a fixed point at one end and having a freeend arranged in attractive relation to said frame, means for magnetizingsaid frame to attract said armature, and means for restrainingoscillations of said armature comprising a yoke pivotally mounted at apoint spaced from the said one end of said armature and having an armengaging one side of said armature intermediate the ends thereof, andresilient means mounted upon said yoke and having a free end engagingthe other side of said armature.

7. In a circuit controller, a magnetizable frame having a core portionand a portion forming a support spaced from said core portion, a coilmounted upon said core portion for magnetizing said frame, a cantileverspring mounted upon said support and carrying at its free end amagnetizable armature in attractive relation to said core portion, and ayoke pivotally mounted at a point spaced from said support, said yokebeing provided with an arm engaging one side of said armature and withresilient means engaging the other side of said armature at a pointspaced along said armature from the point of.

engagement of said arm.

8. In a circuit controller, a supporting member, a member mounted uponsaid supporting member for oscillatory movement about its point ofsupport, and a yoke pivotally mounted at a point spaced from said pointof support, said yoke being provided with an arm& engaging one side ofsaid member and with resilient means engaging the other side of saidmember at a point spaced from the point of engagement of said am.

9. In a circuit controller, a magnetizable sub-- stantially U-shapedframe having one leg forming a core portion and another leg forming asupporting member, a coil mounted upon said core portion for magnetizingsaid frame, a cantilever spring mounted upon said supporting member andcarrying at its free end a magnetizable armature arranged for lateralmovement with respect to said core member, a bracket mounted upon saidsupporting member, a yoke having one arm pivotally mounted upon saidbracket and another arm engaging one side of said armature, and a springfinger attached to said pivoted arm of said yoke, the free end of saidspring finger being arranged to engage the other side of said armatureat a point spaced along said armature i from the point of engagement ofsaid arm.

10. In a circuit controller, a magnetizable frame having a core portionprovided with a pole face and a portion forming a supporting memberspaced from said pole face, a cantilever spring mounted upon saidsupporting portion and carrying a magnetizable armature member having anend located in attractive relation to and biased to a normal positionspaced laterally from said pole face, said pole face being so shaped asto provide a continuously decreasing air gap as said armature endapproaches said face, a bracketmounted upon said supporting member, ayoke pivotally mounted upon said bracket and having an arm engaging saidarmature member at a point intermediate said end and said cantileverspring. and a spring finger mounted uponsaid yoke and having an endengaging the other side of said armature at a point spaced along saidarmature from the point of engagement of said arm.

11. A motor starting relay comprising a pair of normally open switchcontacts arranged to be closed in response to a high surge of electriccurrent and to be reopened upon a diminution of said current to apredetermined lower value, a

magnetizable frame having a core portion, an I armature for controllingsaid contacts, said armature having one and mounted upon said frame anda substantially rigid free end movable with respect to said core portionand arranged to be attracted to thereby, an operating coil mounted uponsaid core portion for magnetizing said frame, and means for restrainingoscillation of said armature comprising resilient means pivotallymounted upon said frame at a point spaced from said one end of saidarmature slidably to engage said free end of said armature.

12. A motor starting relay comprising fixed and movable contactsarranged to be engaged upon a high surge of electric current and to bereopened upon a diminution of said current to a predetermined lowervalue, a flat magnetizable substantially U-shaped frame having a twistedportion forming a magnet core and a portion forming a supporting memberspaced from said magnet core, a magnetizable armature mounted upon saidsupporting member for lateral movement with respect to said magnet core,said armature carrying said movable contact, an operating coil mountedupon said core member. a bracket mounted upon said supporting member,and means pivotally mounted upon said bracket for restrainingoscillation of said armature, said means comprising a substantiallyU-shaped yoke having a spring finger mounted at one side thereof withits free end directed toward the other side thereof and arranged toembrace said armature between said free end of said spring finger andsaid other side of'said U-shaped yoke.

13. In a circuit controller, a fiat substantially U-shaped magnetizableframe having a twisted portion forming a magnet core and a portionforming a supporting member spaced from said magnet core, said magnetcore terminating in a sloped pole face, a m'agnetizable armatureresiliently mounted upon said supporting member for lateral movementwith respect to said pole face, said armature being biased to a positionspaced from said pole face, and an energizing winding mounted upon saidmagnet core for magnetizing said core to attract said armature,

whereby the effective width of said pole face is increased with respectto the path of travel of said armature by the angular disposition ofsaid magnet core and the air gap between said armature and said poleface continuously decreases as said armature approaches said pole facedue to the angular disposition of said pole face thereby to minimizeoscillation of said armature.

EDGAR H. AYERS. WILBUR W. WARNER.

